An oximeter calculates blood oxygen saturation levels within a living being from the different rates at which oxygenated hemoglobin (oxyhemoglobin) and reduced hemoglobin (deoxyhemoglobin) within vascular tissue of the living being absorb light of different wavelengths. Typically, two wavelengths of light are used where one wavelength is much less sensitive to blood oxygen saturation levels than the other. The wavelength of light that is less sensitive to oxygen saturation levels serves as a constant against which the wavelength of light that is more sensitive to oxygen saturation levels is compared in order to calculate blood oxygen saturation levels.
The measurement of oxygen saturation levels (“oximetry”) is a critical physiologic measurement for critical care patients. Presently, sensors for use with oximeters to measure oxygen saturation levels in vascular tissue are designed for placement on a finger, ear lobe, foot, or in an outer portion of the auditory canal. These sensors are subject to motion artifacts that may result in inaccurate measurements. Accordingly, improved oximetry methods and apparatus are needed that are not subject to this limitation. The present invention addresses this need among others.